serial: kgdb_nmi: remove redundant initialization of variable c

The variable c is being initialized with a value that is never
read, it is being updated later on. The assignment is redundant and
can be removed.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Addresses-Coverity: ("Unused value")
Link: https://lore.kernel.org/r/20210513230224.138859-1-colin.king@canonical.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/kgdb_nmi.c

@@ -115,7 +115,7 @@ static void kgdb_tty_recv(int ch)
 static int kgdb_nmi_poll_one_knock(void)
 {
 	static int n;
-	int c = -1;
+	int c;
 	const char *magic = kgdb_nmi_magic;
 	size_t m = strlen(magic);
 	bool printch = false;